The mitochondrial inhibitor oligomycin induces an inflammatory response in the rat knee joint

[Abstract] Background. Recent findings support a connection between mitochondrial dysfunction and activation of inflammatory pathways in articular cells. This study investigates in vivo in an acute model whether intra-articular administration of oligomycin, an inhibitor of mitochondrial function, induces an oxidative and inflammatory response in rat knee joints. Methods. Oligomycin was injected into the rat left knee joint on days 0, 2, and 5 before joint tissues were obtained on day 6. The right knee joint served as control. Results were evaluated by macroscopy and histopathology and by measuring cellular and mitochondrial reactive oxygen species (ROS), 4-hydroxy-2-nonenal (4-HNE, a marker of lipid peroxidation), nuclear factor erythroid 2-related factor 2 (Nrf2), and CD68 (macrophages) and chemokine levels. The marker of mitochondrial mass COX-IV was also evaluated. Results. The macroscopic findings showed significantly greater swelling in oligomycin-injected knees than in control knees. Likewise, the histological score of synovial damage was also increased significantly. Immunohistochemical studies showed high expression of IL-8, coinciding with a marked infiltration of polymorphonuclears and CD68+ cells in the synovium. Mitochondrial mass was increased in the synovium of oligomycin-injected joints, as well as cellular and mitochondrial ROS production, and 4-HNE. Relatedly, expression of the oxidative stress-related transcription factor Nrf2 was also increased. As expected, no histological differences were observed in the cartilage; however, cytokine-induced neutrophil chemoattractant-1 mRNA and protein expression were up-regulated in this tissue. Conclusions. Mitochondrial failure in the joint is able to reproduce the oxidative and inflammatory status observed in arthritic joints.Instituto de Salud Carlos III; 09/02340Instituto de Salud Carlos III, RD12/0009/0018, RIERGalicia. Consellería de Innovación, Industria e Comercio; PXIB916357PRInstituto de Salud Carlos III; PI12/02771Xunta de Galicia; PS09/56Galicia. Consellería de Economía e Industria; INCITE 09E1R916139ESGalicia. Consellería de Economía e Industria; IN845B2010/176Galicia. Consellería de Economía e Industria; 10CSA916035P

The mitochondrial inhibitor oligomycin induces an inflammatory response in the rat knee joint

[Abstract] Background. Recent findings support a connection between mitochondrial dysfunction and activation of inflammatory pathways in articular cells. This study investigates in vivo in an acute model whether intra-articular administration of oligomycin, an inhibitor of mitochondrial function, induces an oxidative and inflammatory response in rat knee joints. Methods. Oligomycin was injected into the rat left knee joint on days 0, 2, and 5 before joint tissues were obtained on day 6. The right knee joint served as control. Results were evaluated by macroscopy and histopathology and by measuring cellular and mitochondrial reactive oxygen species (ROS), 4-hydroxy-2-nonenal (4-HNE, a marker of lipid peroxidation), nuclear factor erythroid 2-related factor 2 (Nrf2), and CD68 (macrophages) and chemokine levels. The marker of mitochondrial mass COX-IV was also evaluated. Results. The macroscopic findings showed significantly greater swelling in oligomycin-injected knees than in control knees. Likewise, the histological score of synovial damage was also increased significantly. Immunohistochemical studies showed high expression of IL-8, coinciding with a marked infiltration of polymorphonuclears and CD68+ cells in the synovium. Mitochondrial mass was increased in the synovium of oligomycin-injected joints, as well as cellular and mitochondrial ROS production, and 4-HNE. Relatedly, expression of the oxidative stress-related transcription factor Nrf2 was also increased. As expected, no histological differences were observed in the cartilage; however, cytokine-induced neutrophil chemoattractant-1 mRNA and protein expression were up-regulated in this tissue. Conclusions. Mitochondrial failure in the joint is able to reproduce the oxidative and inflammatory status observed in arthritic joints.Instituto de Salud Carlos III; 09/02340Instituto de Salud Carlos III, RD12/0009/0018, RIERGalicia. Consellería de Innovación, Industria e Comercio; PXIB916357PRInstituto de Salud Carlos III; PI12/02771Xunta de Galicia; PS09/56Galicia. Consellería de Economía e Industria; INCITE 09E1R916139ESGalicia. Consellería de Economía e Industria; IN845B2010/176Galicia. Consellería de Economía e Industria; 10CSA916035P

Resveratrol y artritis reumatoide: efecto protector en un modelo animal de artritis y estudio de sus propiedades antiinflamatorias en sinoviocitos artríticos humanos en cultivo

[Resumo]Neste traballo estudouse o efecto do resveratrol na artrite reumatoide (AR) in vivo, nun modelo animal de artrite inducida por antíxeno (AlA), e in vitro, en sinoviocitos artríticos humanos en cultivo. Para o estudo in vivo do efecto do resveratrol nun modelo AlA en ratas, éste administrouse dun xeito oral durante dous meses antes da indución da artrite e ata o remate do estudo, dous días despois da indución, coincidindo coa fase aguda da enfermidade. Atopouse que o resveratrol estaba a reducir os principais signos da patoloxía da AR. Así, demostrouse como o resveratrol reduxo a hiperplasia sinovial, o infiltrado de células inmunes na articulación e a expresión dos principais mediadores inflamatorios, ademáis de diminuir o dano oxidativo mediante un aumento na actividade das enzimas antioxidantes. Todo isto viuse reflexado nunha redución da inflamación presente nos xeonllos dos animais trala indución da artrite. Estes resultados suxiren ao resveratrol como unha nova estratexa terapéutica para o trata mento da AR. No estudo in vitro, avaliouse o efecto do resveratrol na resposta inflamatoria inducida pola citocina IL-ll3 en sinoviocitos artríticos humanos en cultivo. Demostrouse como o resveratrol estaba a diminuír a expresión de numerosos xenes que participan no proceso inflamatorio, incluídos aqueles que foron avaliados no modelo AlA, corroborando así in vitro os estudos realizados in vivo. Tamén se avaliou a expresión xénica das distintas sirtuinas e a súa modulación polo resveratrol en sinoviocitos artríticos humanos, obtendo unha tendencia do resveratrol a aumentar a expresión das sirtuinas 1, 2 e 3 baixo condicións proinflamatorias.[Resumen] En este trabajo se estudió el efecto del resveratrol en la artritis reumatoide (AR) in vivo, en un modelo animal de artritis inducida por antígeno (AlA), e in vitro, en sinoviocitos artríticos humanos en cultivo. Para el estudio in vivo del efecto del resveratrol en un modelo AlA en ratas, éste se administró de manera oral durante dos meses antes de la inducción de la artritis y hasta el final del estudio, dos días después de la inducción, coincidiendo con la fase aguda de la enfermedad. Se observó que el resveratrol era capaz de reducir los principales signos de la patología de la AR. Así, se demostró como el resveratrol disminuyó la hiperplasia sinovial, el infiltrado de células inmunes en la articulación y la expresión de los principales mediadores inflamatorios, además de disminuir el daño oxidativo mediante un aumento en la actividad de las enzimas antioxidantes. Todo esto se reflejó en una reducción de la inflamación presente en las rodillas de los animales después de la inducción de la artritis. Estos resultados sugieren al resveratrol como una nueva estrategia terapéutica para el tratamiento de la AR. En el estudio in vitro, se analizó el efecto del resveratrol en la respuesta inflamatoria inducida por la citocina IL-l~ en sinoviocitos artríticos humanos en cultivo. Se demostró que el resveratrol era capaz de disminuir la expresión de numerosos genes que participan en el proceso inflamatorio, incluidos aquellos que fueron analizados en el modelo AlA, corroborando así in vitro los estudios realizados in vivo. También se analizó la expresión génica de las distintas sirtuinas y su modulación por el resveratrol en sinoviocitos artríticos humanos, observando como el resveratrol tiende a aumentar la expresión de las sirtuinas 1, 2 Y 3 en condiciones proinflamatorias.[Abstract] In the present study, the effect of resveratrol in rheumatoid arthritis (RA) was evaluated in vivo, in an antigen-induced arthritis (AlA) animal model, and in vitro, in cultured human arthritic synoviocytes. For the in vivo study of resveratrol effect in an AlA model in rats, resveratrol was orally administered from two months before arthritis induction until the end of the experiment, two days after the induction, coinciding with the acute phase of the disease. Resveratrol was able to reduce the hallmarks of RA pathology. In this way, it was demonstrated that resveratrol decreased synovial hyperplasia, immune ce lis infiltration into the joint and proinflammatory mediators express ion, as well as the reduction of oxidative damage through increasing antioxidant enzymes activity. AII these features was corroborated with a decrease in knee joint inflammation after arthritis induction. These results suggest that resveratrol could be a new therapeutic strategy in the treatment of RA. In the in vitro study, the effect of resveratrol in the inflammatory response induced by the cytokine IL-1~ in cultured human arthritic synoviocytes was anlyzed. It was demonstrated that resveratrol reduced the express ion of several genes involved in the inflammatory process, including those analyzed in the AlA model, thus confirming in vitro the results obtained in vivo. Gene expression of the different sirtuins was evaluated, as well as their modulation by resveratrol in human arthritic synoviocytes. It was observed that resveratrol tends to increase sirtuin 1, 2 and 3 expression under proinflammatory conditions